Transport module

ABSTRACT

A front-opening wafer transport module has a container portion with transparent shell and a central support structure which includes a machine interface exposed at the bottom of the module and integral wafer support columns extending upwardly in the container portion for supporting wafers. Additionally, the side walls of the shell have recessed portions with engagement members that cooperate with engagement members on removable handles. The handles utilize detents to lock into place in the recesses on the side walls of the carrier. Attachment of the handles to the side walls is accomplished without breaks between the interior and exterior of the module and without separate fastners.

This application is a Continuation of application Ser. No. 10/848,096,filed May 18, 2004, which will issue May 13, 2008, as U.S. Pat. No.7,370,764, which is a Continuation-in-Part of application Ser. No.09/476,546, filed Jan. 3, 2000, which is a Continuation of applicationSer. No. 08/891,644, filed Jul. 11, 1997 issued as U.S. Pat. No.6,010,008 which are hereby incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

This invention relates to carriers for semiconductor wafers and moreparticularly it relates to a closeable container for storing andtransporting wafers.

Sealable enclosures, generally termed transport modules, have beenutilized in the semiconductor processing industry for a number of yearsfor storing and transporting wafers between processing steps and/orbetween facilities. Semiconductor wafers are notoriously vulnerable todamage from contaminants such as particles. Extraordinary measures aretaken to eliminate contaminants in cleanrooms and other environmentswhere semiconductor wafers are stored or processed into circuits.

For wafers in the range of 200 mm and smaller, containers known as SMIFpods (standardized mechanism interface) have been utilized to provide aclean sealed mini-environment. Examples of these pods are shown in U.S.Pat. Nos. 4,532,970 and 4,534,389. Such SMIF pods typically utilize atransparent box-shaped shell with a lower door frame or flange definingan open bottom and a latchable door. The door frame clamps ontoprocessing equipment and a door on the processing equipment and thelower SMIF pod door closing the open bottom are simultaneously lowereddownwardly from the shell into a sealed processing environment in saidprocessing equipment. A separate H-bar carrier positioned on the topsurface inside of the SMIF pod door and loaded with wafers is loweredwith the pod door for accessing and processing said wafers. In such podsthe weight of the wafers would be directly on the door during storageand transport.

The semiconductor processing industry is moving toward utilization oflarger and heavier wafers, specifically 300 mm wafers. Transport modulesfor such modules, by way of developing industry standards, will utilizea front opening door for insertion and removal of the wafers as opposedto a bottom door that drops downwardly from the module. The door wouldnot support the load of the wafers, rather a container portion whichwould include a clear plastic (such as polycarbonate) shell and othermembers or supporting the wafers molded from a low particle generatingplastic (such as polyetheretherketone) would carry the load of thewafers. Such container portions necessarily are made from multiplecomponents assembled together.

In handling and processing semiconductor wafers, static electricity is acontinuing concern. Electrostatic discharges can damage or ruinsemiconductor wafers. Therefore, means must be taken to minimize anysuch generation of potentials which may cause static electricdischarges. H-bar carriers have been manufactured with convention staticdissipative materials such as carbon filled polyetheretherketone (PEEK)and polycarbonate (PC).

The developing industry standards for such 300 mm modules require amachine interface, such as a kinematic coupling, on the bottom of themodule to repeatedly and with precision align the module with respect tothe processing equipment. This allows robotic handling means to engagethe door on the front side of the module, open the door, and with thenecessary amount of precision grasp and remove specific horizontallyarranged wafers. It is highly critical to have the wafers positioned ata particular height and orientation with reference to the equipmentmachine interface such that the wafers will not be located and damagedduring the robotic withdrawal and insertion of said wafers.

Due to inconsistencies in molding plastic parts assembly of such plasticparts lead to inconsistencies, such as open cracks between parts and thestacking of the tolerances of each individual part leading toundesirable variations in critical dimensions.

Known front opening 300 mm transport modules utilize multiple componentparts including multiple components between the equipment interface andthe wafer supports. This can lead to difficulty in producing moduleswith acceptable tolerances between the wafer planes and the equipmentinterface. Additionally, such modules have a path to ground from thewafer shelves to the equipment interface through several differentcomponents including metallic screws.

The 300 mm wafers are substantially greater in size and weight than the200 mm modules; therefore, a structurally stronger module fortransporting batches of wafers is required. Typically with the 200 mmSMIF pods the module was simply carried manually by grasping the loweredges at the juncture of the shell door flange and the door. Handleshave been provided on the top of the shell portion for bottom openingpods. For carrying the larger, heavier, and bulkier modules for 300 mmwafers side handles are appropriate. For certain applications, themovement of the 300 mm module may be exclusively by way of robotic meansthus not requiring handles or other means for manually transporting thecontainer. Thus, a robotic lifting handle should be provided and anymanual lifting handles should be easily removable.

Additionally, due to the high susceptibility of wafers to contaminationby particles, moisture or other contaminants it is ideal to have aminimal number of potential entry paths to the interior of the module.Paths or breaks in the plastic between the interior and exterior of thepod such as for fasteners or at the junction of separate component partsof the module are to be avoided. Any such path required should beadequately sealed.

Additionally, the use at any location in the pod of metallic fastenersor other metal parts are highly undesirable in semiconductor wafercarriers or containers. Metallic parts generate highly damagingparticulates when rubbed or scrapped.

SUMMARY OF THE INVENTION

A front-opening wafer transport module has a container portion withtransparent shell and a central support structure which includes amachine interface exposed at the bottom of the module and integral wafersupport columns extending upwardly in the container portion forsupporting wafers. Additionally, the side walls of the shell haverecessed portions with engagement members that cooperate with engagementmembers on removable handles. The handles utilize detents to lock intoplace in the recesses on the side walls of the carrier. Attachment ofthe handles to the side walls is accomplished without breaks between theinterior and exterior of the module and without separate fastners.

A feature and advantage of the invention is that there are no stackingof tolerances among parts relative to the machine interface level andthe levels of the wafers on the wafer shelves. Where multiple componentsdefine the machine interface level and the wafer levels, each part has aseparate manufacturing tolerance and when such components are assembledinto the module the tolerances are cumulative. This translates into ahigher rejection of individual parts and/or a higher rejection level ofassembled modules. The instant invention utilizes a single integralcomponent for the machine interface and the wafer support members.

Another advantage and feature of the invention is that a non-interruptedpath-to-ground extends from each wafer support shelf to the machineinterface.

Another object and advantage of the invention is that the centralsupport structure which holds the wafers is assembled into the shellthrough a lower opening and is secured in place by a rotation of thecentral support structure with respect to the shell. No metallicfasteners are used.

Additionally, the central support structure engages and locks at the topof the shell by way of a top portion with a collar that extends into anaperture in the top of the shell and robotic lifting flange thatslidably engages the top portion of the central support structure andalso thereby non-rotatably locks the support structure to the shell.Again, no metallic fasteners or components are used.

Another object and advantage of the invention is that the breaks oropenings in the module between the interior and exterior are sealed suchas by elastomeric seals. The breaks or openings other than at the frontdoor are circular in shape and are sealed such as by O-rings.

Anther object and advantage of the invention is that handles may beeasily added and removed to the module without utilizing metallicfasteners or other separate fasteners and without breaks or openings inthe solid side walls.

Another object and advantage of the invention is that the componentparts may be easily disassembled for cleaning and/or replacement formaintenance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a transport module plotting theinvention.

FIG. 2 is a perspective view of the container portion of a transportmodule embodying the invention.

FIG. 3 is a perspective view of the inside facing cover of the door forthe transport module embodying the invention.

FIG. 4 is an exploded view showing the various component parts of atransport module.

FIG. 5 is a perspective view of a container portion of the transportmodule.

FIG. 6 is a perspective view of a guide-in structure.

FIG. 7 is a bottom view of the shell of the container portion.

FIG. 8 is a top plan view of the central support structure.

FIG. 9 is a cross-sectional view taken at line 9-9 of FIG. 8.

FIG. 10 is a cross-sectional view taken at line 10-10 of FIG. 7.

FIG. 11 is a front elevational view of the top portion of the centralsupport structure.

FIG. 12 is a front elevational view of the second connecting memberincluding the robotic flange.

FIG. 13 is a cross-sectional view taken at line 13-13 of FIG. 8.

FIG. 14 is a front elevational view of the handle.

FIG. 15 is a side elevational view of the handle.

FIG. 16 is a side elevational view of a portion of the shell showing therecess for the handle.

FIG. 17 is a cross-sectional view taken at line 17-17 of FIG. 6.

FIG. 18 is an elevational view of an alternative embodiment of theinvention focusing on the handle and recess for receiving the handle.

FIG. 19 is a cross-sectional view taken at line 19-19 of FIG. 18.

FIG. 20 is a cross-sectional view taken at line 20-20 of FIG. 18.

FIG. 21 is a side elevational view of a portion of the module showing analternative embodiment of the handle.

FIG. 22 is a side elevational view of the handle.

FIG. 23 is a cross-sectional view taken at line 23-23 of FIG. 21.

FIG. 24 is a cross-sectional view taken at line 24-24 of FIG. 21.

DETAILED SPECIFICATION

Referring to FIGS. 1, 2, and 3 a composite transport module for wafersgenerally designated with the numeral 20 is principally comprised of acontainer portion 22 and a door 24. The container portion includes arobotic lifting flange 26 and manual lifting handles 28. The door 24 hasmanual opening handles 30 and a key slot 32 which provides capability ofbeing opened by way of robotic means. FIG. 2 shows the container portionand its open interior 36 with a plurality of wafers 38 shown supportedand axially arranged in said open interior. FIG. 3 shows the insidesurface 40 of the door. The door has a pair of wafer restraints 42 whichengage and restrain the wafers when the door is in place. The waferretainers are formed of flexible teeth 44 which are of resilient moldedplastic. The door 24 fits within a door flange 46 on the containerportion 22 and utilizes latches 48 which extend and retract from thedoor enclosure 50 to engage recesses 54 in the door flange. The door hasa pair of internal latch mechanisms 53 which operate independently ofeach other and by way of the manual door handle 30 or key slot 32. FIG.3 also depicts a piece of processing equipment 55 with a moduleinterface portion 56 on which the transport module 20 is engaged.

Referring to FIG. 4, an exploded perspective view of the transportmodule which show details of the construction and the various componentparts. The container portion 22 is comprised principally of a shell 58and a central support structure 60.

The shell 58 has a top 64 with an aperture 66, a bottom 68 with a loweropening 70, an open front side 72, a left side wall 74, and a right sidewall 76 both with handle receiving portions configured as recesses 78extending inwardly. Notably, the recesses project into the interior buthave no cracks, breaks, openings or apertures between the interior 74and the exterior of the container. The side walls may be continuous andsolid. The handle receiving portions include a recessed planar portion80 which is part of the side walls. Shelves may be as shown in U.S.patent application Ser. No. 09/523,745 to David Nyseth filed Mar. 13,2000. Said application is hereby incorporated by reference.

The central support structure 60 is comprised of a bottom portion withan equipment interface 86 configured as a plate with three interfacestructures 88 which comprise a kinematic coupling. Integral with themachine interface portion 86 are a pair of wafer support columns 92 eachof which comprise a plurality of shelves 94 and defining a waferreceiving region 95. Each shelf having wafer engagement portions 96. Thewafer support columns 92 are integral with a top portion 100 whichincludes a spanning member 101 which extends between the tops 98 of thesupport columns 92 and also includes a first connecting member 104.

The central support structure 60 assembles upwardly into the loweropening 70 of the shell 58 with the first connecting member extendingupwardly through the aperture 66 on the top 64 of the shell 58. Thesecond connecting member 106 slidably engages on the first connectingmember 104 for retention of the central support structure in the shell.A second connecting member 106 which is integral with a robotic liftinghandle 108 configured as a flange. The shell also includes firstengagement members 112 as part of a support structure engagement portion113 which engage with second engagement members 114 as part of a shellengagement portion 115 on the central support structure. Thesecooperating engagement members also secure the central support structureto and within the shell. A first O-ring 118 engages between the topportion 100 of the central support structure and the top 64 of the shellto create a seal thereabout. Similarly, a second O-ring 120 sealsbetween the machine interface portion 86 and the bottom 68 of the shell.Referring to FIG. 5, the transport module 20 with the door 24 removedreveals the open interior 36 and the various interior structures. Thisparticular embodiment utilizes a guide-in structure 122 which engageswith rails 124, 126 on the interior surface 130 of the side walls 74, 76and integral with same. Shown in FIG. 6 each guide-in structure utilizeselongate engagement members 136 to fit within the rails 124, 126. theguide-in structure 122 includes teeth 138 which define slots 140 whichare substantially parallel to and correlate with each of the slots 142as defined by the shelves 94 of said wafer support columns 92. Typicallythe guide-in members are intended to be used when there is manualinsertion of the wafers as opposed to robotic insertion. The guide-instructures 122 can also be expanded to support each wafer during more ofeach wafer's travel into and out of the transport module.

As shown best in FIGS. 4, 5 and 8, the lower portion of the centralsupport structure includes a machine interface plate 86 which has aplanar top surface 170 and a step 174 down to a lower planar surface176. Note that the lower planar surface 176 confronts theinwardly-extending portion 180 of the bottom 68 of the shell 58. Notethat this inwardly-extending portion 180 does not extend uniformly as achord across the lower generally circular opening 70; rather a furtherinset portion 184 allows the central support structure 60 to be put inplace slightly rotated off the fully aligned position to provide for theinsertion of the second engagement members into position intermediatethe first engagement member 112 on the shelf. The central supportstructure 60 can then be partially rotated to the assembled position asshown in FIG. 5.

Referring to FIGS. 4, 8, 11 and 12, details of the elements andcomponents which comprise the connection between the top portion 100 ofthe central support structure 60 and the shell 58 are shown in detail.The top portion 100 has a pair of first connecting members 104 whichhave a generally T-shaped cross section as best shown in FIG. 11. Thefirst connecting members 104 engage with and fit into slots 186 alsohaving a T-shaped cross section in the second connecting member 106which is part of the robotic lifting flange 108. After the centralsupport structure 60 is inserted into place in the shell 58 and rotatedto the proper alignment position, the collar or neck 188 of the topportion 100 will extend through the aperture 66 and will confront theinner edge 190 which defines said aperture. The smaller O-ring 118 fitsinto the O-ring groove 194 on said neck 188 and creates a seal with theshell at the inner edge 190. The phantom line of FIG. 11 shows therelationship of the top 64 of the shell 58 as it confronts the neck 188of the top portion of the central support structure 60. Thus, when thesecond connecting member 106 is engaged with the first connectingmembers 104, the top 64 of the shell 58 is sandwiched between said firstengagement member 106 and the top portion 100 of the central supportstructure. The second connecting member 106 may be locked in place onthe first connecting member 104 by way of an appropriately positioneddetent or nub 202 such as shown in FIG. 4 on the top surface 203 of thetop of the shell 58. Alternatively or additionally, screws 206 may beutilized which would extend through the robotic pick-up flange 108through the second connecting member 106 and into the threaded holes 208in the first connecting members 106. The screws are appropriately nylonas opposed to a metallic material.

The equipment interface 86 as best shown in FIGS. 4, 5 and 8, includes akinematic coupling 90 formed by way of the equipment engagement portion88. Referencing FIG. 13 which is a cross section through one suchstructure, the lower surface 220 includes a pair of angled faces 222,224 defining a groove 225 which would engage partial, spherical surfaceson the equipment, not shown. Alternatively, the interface portion of thecentral support structure 60 could include said three partial spheresand the cooperating equipment include the grooves formed by angledfaces. Alternatively, the equipment interface 86 could include alternateconfigurations and features to interface with the associated equipment.

Referring to FIGS. 2, 14, 15, 16, and 17, details of the constructionand assembly of the removable manual lifting handles 28 are shown. Thehandle comprises a gripping portion 240 and a shell engagement portion242. The shell engagement portion 242 utilizes resilient portions 244with detents 246 and stops 248. The detents 246 have a wedge portion 250which facilitates installation of the handle into the recesses 78 androtation under the second engagement structures 254 on the shell 58. Thesaid second engagement structures comprises a pair of inwardly-extendingmembers 255 configured as guide strips which correspond to the extendedportion 258 on the handle engagement portion 242 when said handle is ina locked position in said recess 78. In such a locked position, thedetents 246 and the stops 248 are at opposite ends of the guide strips255. The recess 78 is defined by way of a planar portion 262 integralwith a circumferential recess wall configured as a ring-shaped portion264 which is integral with the shell. The guide members 255 are integralwith and extend from said ring portion 264. Said configuration allowseasy installation simply by placement of the handles 28 into therecesses 78 shown in FIG. 16 with the outwardly-extending portionspositioned intermediate the guide members 255 and then rotating in aclockwise direction said handle with the first engagement structurewhereby the extending portions 258 including the detent 246 rotateunderneath the guide members 255 until the detents 246 snap into placeat their seating positions 269 at which point the stops 248 are in theirrespective seating positions 270.

Significantly, this particular configuration allows easy installationand removal of the handle such as for cleaning or storage or when arobotic application does not require use of the handle. Additionally,the integrity of the separation between the interior of the transportmodule and the exterior is not affected. In other words, there are nobreaks, openings or fasteners through the side walls to accomplish theconnection of the handle to said shell.

Referring to FIG. 18, engagement structure 275 includes an alternativeembodiment of the removable handle 28 shown. This embodiment againutilizes a recess 78 extending inwardly in the side wall 74 with aplanar portion 262 at the bottom of said recess. A recess wall or borderportion 274 extends around and defines said recess and is integral withthe planar portion 262 and the side wall 74. First engagement member 276configured as four tabs extending inwardly from the recess wall 274. Themanual lifting handle 28 comprises a gripping portion 240 and theengagement portion 254 which includes planar portion 277 withresiliently-flexible portions with detents 284. The manual handle 28 isinserted into the recess 78 such that the resilient portions 280 areplaced intermediate the tabs 276 and the handle is then slid to the leftsuch that the detents extend under said tabs and slide until they reachtheir locking position as shown in FIG. 18. Again, this configurationdoes not breach the integrity of the side wall separating the interiorof the transport module from the exterior. Other configurations are alsoavailable for utilization of the handle with cooperating engagementmembers utilizing detents. The use of the detents provides a high levelof flexibility in placement and removal of the handles and allowsexchange of different sizes of handles, for example, for differentoperators.

The shell portion of the material is preferably injection molded formpolycarbonate or polyetherimide or the like. The central supportstructure is also ideally integrally injection molded and may be formedfrom carbon fiber filled PEEK or similar materials, ideally whichprovide a static dissipative feature. The handles may be injectionmolded from polycarbonate or polyetherimide. The top second connectingmember including the robotic lifting handle may be also formed fromcarbon fiber filled PEEK or other static dissipative injection moldedmaterial.

The mechanisms utilized for latching the doors can be varied and may besuch as shown in U.S. Pat. No. 4,995,430 to Anthony C. Bonora et al.,U.S. Pat. No. 5,915,562 to Nyseth, or similar mechanisms.

Referring to FIGS. 19 and 20, cross-sectional views are taken throughthe shell and handle member as shown in FIG. 18. Note the detent 284includes a wedge-shaped portion 250 to aid insertion under theengagement member 276. Referring to FIGS. 21, 22, 23, and 24, variousviews are shown of an additional embodiment of the handle member and thecooperating engagement structure of the shell. In this particularembodiment the detent members 300 extend normally from the recessedplanar portion 304 and thus normally from the side wall of the shell.The detent members generally comprise a pair of angled or wedge-shapedportions 308 sized to fit into a cooperating second engagement member312 utilizing a circular aperture 314.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof; and it is,therefore, desired that the present embodiment be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than to the foregoing description to indicatethe scope of the invention.

1-21. (canceled)
 22. A sealable enclosure for receiving and holding aplurality of wafers horizontally, the enclosure comprising: a containerportion with a top, a bottom, a back, an open front, an open interiorand comprising a forwardly projecting door flange with a plurality ofrecesses therein, a pair of sides, a plurality of shelves positioned inthe open interior at each side of the container portion for holding thewafers axially aligned in said interior; and a door for fitting withinthe door flange and sealingly closing the open front, the doorcomprising a plurality of latch mechanisms that extend and retractlatches to engage the recesses in the door flange, each latch mechanismincluding a manual opening handle for operating the latch mechanismmanually and each latch mechanism also including structure defining akey slot for operating the latch mechanism robotically.
 23. Theenclosure of claim 22, further comprising a kinematic coupling on thebottom of the enclosure.
 24. The enclosure of claim 22, wherein theplurality of shelves and the kinematic coupling are integrally formed ofstatic dissipative material, thereby forming an uninterrupted electricalpath to ground.
 25. The enclosure of claim 22, the container portiondefining a handle receiving structure on an outside surface of each ofthe pair of sides, each handle receiving structure adapted to receive aremovable handle and comprising a pair of spaced apart linear guidestrips, whereby the removable handle is linearly slidable between theguide strips to couple the removable handle with the container portion.26. The enclosure of claim 25, wherein each linear guide strip comprisesa planar portion oriented generally parallel with the side and spacedapart from the side, the planar portions of the each of the spaced apartguide strips being vertically registered and extending toward each othersuch that the guide strips together define a handle receiving slot forlinearly slidingly receiving the handle therein.
 27. The enclosure ofclaim 25, in combination with a pair of handles, wherein each of thehandles is linearly slidably engageable with a separate one of thehandle receiving structures, and wherein each handle comprises a detentfor securing the handle in a favored position.
 28. The enclosure ofclaim 22, wherein an inside facing surface of the door has a centralrecess extending from the top of the door to the bottom of the door andwherein a wafer restraint is positioned in the central recess.
 29. Asealable transport module for receiving and holding a plurality ofwafers horizontally, the module comprising: a container portion with atop, a bottom, a back, a pair of opposing sides, an open front, and anopen interior, the open front being defined by a door frame with aplurality of recesses therein, the container portion further including aplurality of shelves positioned in the open interior proximate each sideof the container portion for holding the wafers axially aligned in saidinterior; and a door selectively engageable in the door frame tosealingly close the open front, the door comprising at least one latchmechanism that extends and retract latches to engage the recesses in thedoor flange, the at least one latch mechanism including means foroperating the latch mechanism manually and the at least one latchmechanism also including means for operating the latch mechanismrobotically.
 30. The module of claim 29, wherein the means for operatingthe at least one latch mechanism manually comprises a manual openinghandle operably coupled with the at least one latch mechanism.
 31. Themodule of claim 29, wherein the means for operating the at least onelatch mechanism robotically comprises structure defining a key slotoperably coupled with the at least one latch mechanism.
 32. The moduleof claim 29, further comprising a kinematic coupling on the bottom ofthe enclosure.
 33. The module of claim 32, wherein the plurality ofshelves and the kinematic coupling are integrally formed of staticdissipative material, thereby forming an uninterrupted electrical pathto ground.
 34. The module of claim 29, the container portion defining ahandle receiving structure on an outside surface of each of the pair ofopposing sides, each handle receiving structure adapted to receive aremovable handle and comprising a pair of spaced apart linear guidestrips, whereby the removable handle is linearly slidable between theguide strips to couple the removable handle with the container portion.35. The module of claim 34, wherein each linear guide strip comprises aplanar portion oriented generally parallel with the side and spacedapart from the side, the planar portions of the each of the spaced apartguide strips being vertically registered and extending toward each othersuch that the guide strips together define a handle receiving slot forlinearly slidingly receiving the handle therein.
 36. The module of claim34, in combination with a pair of handles, wherein each of the handlesis linearly slidably engageable with a separate one of the handlereceiving structures, and wherein each handle comprises a detent forsecuring the handle in a favored position.
 37. The module of claim 29,wherein an inside facing surface of the door has a central recessextending from the top of the door to the bottom of the door and whereina wafer restraint is positioned in the central recess.
 38. A sealableenclosure for transporting a plurality of semiconductor wafers, theenclosure comprising: a container portion with a top, a bottom, a back,a pair of opposing sides, an open front, and an open interior, the openfront being defined by a door frame with a plurality of recessestherein, the container portion further including a plurality of shelvespositioned in the open interior proximate each side of the containerportion for holding the wafers axially aligned in said interior; and adoor selectively engageable in the door frame to sealingly close theopen front, the door comprising at least one latch mechanism thatextends and retract latches to engage the recesses in the door flange,the at least one latch mechanism including a handle and separatestructure defining a key slot, each operably coupled with the latchmechanism to enable the latches to be selectively extended andretracted.
 39. The enclosure of claim 38, the container portion defininga handle receiving structure on an outside surface of each of the pairof sides, each handle receiving structure adapted to receive a removablehandle and comprising a pair of spaced apart linear guide strips,whereby the removable handle is linearly slidable between the guidestrips to couple the removable handle with the container portion. 40.The enclosure of claim 39, wherein each linear guide strip comprises aplanar portion oriented generally parallel with the side and spacedapart from the side, the planar portions of the each of the spaced apartguide strips being vertically registered and extending toward each othersuch that the guide strips together define a handle receiving slot forlinearly slidingly receiving the handle therein.
 41. The enclosure ofclaim 39, in combination with a pair of handles, wherein each of thehandles is linearly slidably engageable with a separate one of thehandle receiving structures, and wherein each handle comprises a detentfor securing the handle in a favored position.